Identification and control of an isolated, but intense focus of lymphatic filariasis on Satawal Island, Federated States of Micronesia, in 2003

Pretrick, Moses, Melrose, Wayne, Chaine, Jean-Paul, Canyon, Deon, Carron, Jaime, Graves, Patricia M., and Bradbury, Richard S. (2017) Identification and control of an isolated, but intense focus of lymphatic filariasis on Satawal Island, Federated States of Micronesia, in 2003. Tropical Medicine and Health, 45 (17). pp. 1-5.

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There is very limited data available on the prevalence of Bancroftian filariasis in the Federated States of Micronesia (FSM). Considerable attempts to eliminate the disease had occurred in the Pacific region by the year 2003, and the prevalence in FSM was thought to be sufficiently low that the region was considered non-endemic. However, a survey conducted in 2003 on an isolated atoll of FSM, Satawal Island, challenged that assumption.

Methods: Participants on Satawal Island were recruited and their blood tested for Wuchereria bancrofti antigen by the filariasis immunochromatographic test (ICT) card and circulating microfilaria by Knott's concentration technique. A survey for active cases of lymphoedema, elephantiasis and hydrocoele was performed and mosquitoes were trapped and dissected to detect larvae of W. bancrofti.

Results: A total of 104 males and 149 females from early teens to mid-80s were tested. Men had a significantly higher prevalence of infection than women in both the ICT test (53 vs 28%; p < 0.001) and by Knott's concentration results (37 vs 11%; p < 0.001). Microfilaria prevalence was higher in subjects ≤ 25 than in those >25 years of age. All persons sampled were treated for LF. No cases of elephantiasis or hydrocoele were detected. No Aedes dissected were positive but three of nine culicine mosquitoes were positive for L1–3 larval stages of W. bancrofti by microscopy. In depth interviews were conducted with residents and chiefs.

Conclusions: This survey showed that even in regions thought to be close to elimination, isolated high intensity foci of lymphatic filariasis may occur. These need to be recognized and control measures instituted such as local MDA as in the current study.

Item ID: 50278
Item Type: Article (Research - C1)
ISSN: 1349-4147
Keywords: filariasis, lymphatic, Wuchereria, elephantiasis, hydrocoele, entomology, mosquitoes, micronesia
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© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

Funders: GlaxoSmithKline
Date Deposited: 19 Sep 2017 23:03
FoR Codes: 32 BIOMEDICAL AND CLINICAL SCIENCES > 3202 Clinical sciences > 320211 Infectious diseases @ 30%
42 HEALTH SCIENCES > 4202 Epidemiology > 420202 Disease surveillance @ 35%
32 BIOMEDICAL AND CLINICAL SCIENCES > 3207 Medical microbiology > 320704 Medical parasitology @ 35%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920109 Infectious Diseases @ 35%
92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920404 Disease Distribution and Transmission (incl. Surveillance and Response) @ 35%
92 HEALTH > 9202 Health and Support Services > 920203 Diagnostic Methods @ 30%
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